This function sets a certificate/private key pair in the gnutls_certificate_credentials_t type. This function may be called more than once, in case multiple keys/certificates exist for the server. For clients that wants to send more than their own end entity certificate (e.g., also an intermediate CA cert) then put the certificate chain in cert_list .

Note that the certificates and keys provided, can be safely deinitialized after this function is called.

If that function fails to load the res type is at an undefined state, it must not be reused to load other keys or certificates.

Note that, this function by default returns zero on success and a negative value on error. Since 3.5.6, when the flag GNUTLS_CERTIFICATE_API_V2 is set using gnutls_certificate_set_flags() it returns an index (greater or equal to zero). That index can be used to other functions to refer to the added key-pair.